The proposed research is intended to study further the catecholamine synthesizing enzyme, dopamine-beta-hydroxylase (DBH), as it pertains to humans. These goals will be accomplished by (1) isolating the enzyme from human tissues (i.e., pheochromocytoma, plasma, adrenal glands); and (2) developing a radioimmunoassay for human DBH in order to help define the relationship of plasma DBH and sympathetic nervous system activity. Human DBH will be isolated from pheochromocytoma via ion-exchange and gel filtration chromatography. An affinity chromatography technique will be developed for purification from plasma and adrenal gland. A radioimmunoassay (RIA) will be developed for the human enzyme, which appears to be immunologically quite different from bovine DBH. This assay will be used for clinical investigation in which plasma DBH will be determined both by RIA and enzymatic assay in normal subjects and subjects with various forms of hypertension. Immunologic and enzymatic activity of plasma DBH will be correlated with urinary catecholamines and catecholamine metabolites before and after acute stresses (in normal subjects and subjects with hypertension). BIBLIOGRAPHIC REFERENCES: Stone, R.A. and DeLeo, J.: Psychotherapeutic Control of Hypertension. New England Journal of Medicine 294: 80-84, 1976. Lilley, J.J., Golden, J. and Stone, R.A.: Adrenergic regulation of blood pressure in chronic renal failure. Jornal of Clinical Investigation 57(5): 1190--1200, 1976.